Impact of thermal annealing inducing oxidation process on the crystalline powder of In₂S₃

Inorganic two-dimensional semiconductor indium sulfide (In₂S₃) has recently attracted considerable attention as a buffer material in the field of thin-film photovoltaics, photo electrochemical cells and other energy-related applications. Compared with this growing interest, however, detailed characterizations of the commercial material are not done. The present investigation deals with the systematic investigation of the physical properties of powdered β-indium sulfide (In₂S₃). The crystalline structure, the composition, and the morphological properties of the samples were characterized using a range of techniques such as X-ray powder diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). X-ray diffraction patterns revealed mixed peaks of In₂S₃ and In₂O₃ for the sample annealed at 400 °C. The In₂O₃ peaks were crystalline with a cubic phase with a (222) preferential orientation. These results were supported by the FTIR, and XPS studies. Thus, a significant correlation was established between the annealing temperature and the TEM images. The main conclusion of the paper opens the possibility of using In₂S₃ layers for solar cells.